The present invention relates to a method and apparatus for automatically forming the wire ends which project from a work piece after a wire or lead has been wound onto the workpiece. More particularly, it concerns a method and apparatus for automatically forming, cutting and trimming the wire ends which project axially from ring-shaped articles such as toroidal cores after a lead or wire has been wound about the core.
As used herein, the term "core" means a ring-shaped article having the plane closed curve cross section of a toroid. The term "wire" as used herein means any material in the form of a flexible strand which is not so supple that it buckles easily when pushed from one end in a lengthwise direction.
Wire wound ferrite cores have been used as electronic components for many years. They are particularly adapted for producing a gapless magnetic field. Inductance coils and transformers can be constructed in this manner. Rheostats can be constructed with cores wound with resistance wire. Very small wire wound cores have also been used as memory elements in computers.
Originally wire was wound onto such cores by hand. Since this operation is both tedious and time consuming, and produces non-uniform results, various automatic core winders have been devised which wind wire onto cores automatically.
Initially, automatic core winders involved a rotating shuttle for carrying the wire at high speed repeatedly through the central aperture of the core. (See, for example, U.S. Pat. No. 2,810,530).
More recently, shuttleless core winders have been developed which do not require insertion of a shuttle through the central aperture of the core. Instead, wire is guided in a coil which extends through the central aperture of the core, and is driven around the guide path to form successive coils or loops which are subsequently tightened on the core by suitable braking or anchoring of the wire ends.
Shuttleless core winders of this type are shown, for example, in U.S. Pat. Nos. 3,985,310 and 4,288,041, both owned by the assignee of the present application, and U.S. Patent Application Ser. No. 610,448, also assigned to the assignee of this application. In these winders, one or more wires can be wound onto a core.
In these core winders, the trailing end of the wire must be cut from the source once sufficient wire has been fed. This is normally done with a suitable cutting device at any time after sufficient turns have been tightened on the core to anchor the trailing wire end (the trailing loop of wire is tightened first in this type of core winder).
There will normally be excess of the wound wire in this technique, since more wires must be formed into loops than will be ultimately wound onto the core, to ensure that there is sufficient wire to be driven around the guide path during the formation of the last turns of the core. In U.S. Pat. No. 4,288,041 and Application Ser. No. 610,448 this excess wire is cut off by directing the leading end of each wire downwardly out of the guide path, and shearing the excess end off once the wire extends tightly from the core in a straight line.
In these and other shuttleless core winders of this general type the core ejected after the winding operation will still have wire ends projecting axially from the inner periphery of each side of the core. It is common for these core ends to be manually shaped, trimmed and tinned before packaging the finished product. This manual finishing procedure is time consuming and labor intensive, and results in a relatively expensive final product which is of inconsistent quality.